The present invention relates to motors in general and more particularly to voice-coil motors.
Voice-coil motors are well known in the art and have been used to power modern linear and rotary actuators in conjunction with servo systems. One prior art voice-coil motor comprises a magnet and a coil coupled through a coil support to an extension arm.
As a current is applied to the coil, a magnetic field is created. This magnetic field opposes a field of the magnet. A repulsion of the two fields results in a force causing movement of the extension arm about a bearing. In one prior art application of this voice-coil motor, a read/write head is coupled to the actuator arm. The movement of the extension arm permits the reading or writing of information with the read/write head using a storage disk.
In the prior art, the bearings comprising the voice-coil motor rotate about a pivot and create friction that slows the speed of rotation of the extension arm. The prior art bearing design also results in an increased mass and size of the voice-coil motor and a concomitant increase in the current required to cause movement of the extension arm.
What is needed, therefore, is an alternative method and/or apparatus with which a motor such as a voice-coil motor may be utilized without encountering the problems of the prior art.
An actuator of the present invention includes a set of generally planar assemblies comprising cross-hinges that are disposed between a set of extended arms and a rigid mounting base. The hinges of the present invention flex about a pivot axis to replace the pivot and bearing assembly of prior art actuators. In an exemplary embodiment the hinges are used in conjunction with a voice-coil motor (xe2x80x9cVCMxe2x80x9d).
The hinges of the present invention are advantageous over prior art bearings as no frictional forces exist between bearing surfaces. In the present invention, hysteresis effects are preferably smaller than the frictional forces of the prior art. The reduced frictional forces of the present invention result in a reduced current as compared to the prior art current required to impart motion with a given force to an arm. In the present invention, the motion includes a rotary motion and a translational motion. In the present invention reduced current requirements permit a reduction in the size of a coil of the motor; the motor may, thus, be made smaller than the prior art. A smaller motor reduces mass such that the arm may move with increased speed and improved operating bandwidth. Also, in the present invention, the hinges may be made smaller than commercially available bearings, and, therefore, the motor of the present invention may be made with a smaller form factor than the prior art.
In one embodiment of the present invention, the hinges constrain the motion of an actuator arm of a voice coil motor such that the arm rotates to deflect a beam of light between an input and an output of an optical switch.
In another embodiment of the present invention, the hinges constrain the motion of an actuator arm of a voice coil motor such that the arm rotates to deflect a beam of light within an optical storage device.